SuperPile 2017 Online Proceedings, (DFI)
Pressed-In Sheets, Secant Piles, and Micropiles Used for Bay-front Mixed-use Development in Newport Beach, Calif.
Takefumi Takuma, Russell Lamb, P.E., and Christopher DellAringa, P.E., Ph.D.
This presentation will highlight the design and construction of a large multi-use building foundation with a highly water-tight basement in liquefiable soft soil in a densely-populated urban area. The Newport Bay Marina Project is a mixed-use development on a 2.5-acre bay front site in a posh urban neighborhood of Newport Beach in southern California. The project consists of building 27 condominium units, 40,000 sf office/retail space, more than 200 underground car parks, and 22 boat slips. The project site is bordered by a small bay, an arterial highway, adjacent low-rise buildings, and a small shipyard. The project is very close to the Newport-Inglewood Fault, which can generate 6.0 to 7.4 magnitude earthquakes and likely cause liquefaction and lateral spreading in a loose sand layer at and near the project site. In addition, the high groundwater level posts another challenge to the project. Based on the above scope of work with the geotechnical/seismic conditions, the structure was designed to have a mat slab foundation supported mostly with micropiles. Sheet piles and secant piles were used for earth retaining as well as a form for permanent concrete walls of the underground parking structures. The Press-in piling method was used for sheet pile installation to minimize vibration and impact to neighboring structures where the pile lines were close to those structures based on the on-site vibration testing that utilized a vibratory hammer. Water jetting was used to facilitate pressing the sheet piles into a deeper dense sand layer. Secant pile installation experienced grout loss and some other difficulties due to the site conditions. The bottom slab was designed to be 2 feet thick with dewatering by 45 units of 40-foot-deep well pumps placed along the perimeter of the project. 624 of 20-inch diameter micropiles were installed to support the structure.
|article #2677; publication #1031 (SP-2017)|